1. Field of the Invention
The present invention relates generally to a cordless charging apparatus, and more particularly, to a cordless charging apparatus for restricting interference between frequencies of a Near Field Communication (NFC) antenna and a resonator of a cordless charging apparatus.
2. Description of the Related Art
In general, a portable terminal refers to a device by which a user can use a mobile communication function, an electronic note function, an Internet connection, and a multimedia function while carrying the device. Various functions have recently been integrated in one mobile communication terminal, which is generally referred to as a smart phone.
Usually, a traffic card, a visitor verifying security card, a credit card, etc. are used for payment or user verification using NFC. Generally, an NFC function is enabled in each of the portable terminals. Thus, a conventional portable terminal includes a separate antenna for performing an NFC function. NFC technology is disclosed in Korean Patent Application No. 2009-126323. In contrast to short range communication such as Bluetooth® or Zigbee®, a communication setting speed of the NFC between communication devices is quick. However, since the NFC is performed at a relatively low frequency band of 13.56 MHz, it is important to achieve a recognition distance in order to enable the NFC function in a portable terminal. A detachable or embedded battery pack is provided in a portable terminal to supply electric power to the portable terminal. A user may charge the battery pack according to a residual amount of power of the battery. In conventional portable terminals, a battery pack is charged through a separate charger, and efforts for commercializing a cordless charging function are constantly being made for the sake of convenience.
Cordless charging technologies include an inductive coupling method using a magnetic field, a capacitive coupling method using an electric field, and a radio frequency wave radiation method. The inductive coupling method is suitable for cordless charging with respect to power efficiency. The inductive coupling type cordless charging is performed by arranging a primary coil provided in a charger and a secondary coil provided in a terminal. The cordless charging technology is disclosed in Korean Unexamined Patent Publication No. 2008-32519. Meanwhile, in order to enable the NFC function and the cordless charging function in one terminal, an NFC antenna element generally having a loop antenna form and a resonator for cordless charging should be mounted to the terminal.
FIG. 1 is an illustration showing one surface of a cordless charging apparatus according to the related art. FIG. 2 is an illustration showing another surface of the cordless charging apparatus of FIG. 1.
Referring to FIGS. 1 and 2, a cordless charging apparatus 10 is provided on an outer side of an NFC antenna element 16. The cordless charging apparatus 10 includes cordless power reception resonators 12 and 15, and a circuit 11a. 
A feeder 13 and a ground 14 (hereinafter, the feeder 13 and the ground 14 will also be referred to as connection terminals 13 and 14) of the cordless power reception resonators 12 and 15 are firmly mounted to a connection terminal 11 connected to the circuit 11a provided on an upper side of the cordless charging apparatus 10 and the NFC antenna 16. That is, the connection terminals 13 and 15 of the cordless charging apparatus 10 and a connection terminal 17 of the NFC antenna 16 are firmly mounted to the connection terminal 11. In more detail, the feeder 13 of the cordless power reception resonators 12 and 15 is provided at one end of the connection terminal 11, and the ground 14 of the cordless power reception resonators 12 and 15 is located close to an opposite side of the connection terminal 11. The feeder 13 and the ground 14 are located close to the connection terminal 11 and face each other. The connection terminal 17 of the NFC antenna 16 is disposed on the connection terminal 11.
Accordingly, the cordless power reception resonators 12 and 15 and a frequency of the NFC antenna 16 electromagnetically interfere with each other severely. That is, performance of the NFC antenna 16 becomes unstable due to a multiplying resonance generated by a frequency radiated from the cordless charging apparatus 10 and a frequency radiated from the NFC antenna 16. Further, an isolation level between the wireless power reception resonators 12 and 15 and the NFC antenna 16 is reduced. Accordingly, a high frequency performance of the cordless power reception resonators 12 and 15 is reduced.